> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Next Closest Time Python Solution with Tests

> Tested Python solution for LeetCode 681 with 18 pytest cases. Generate a practice environment with lcpy.

LeetCode 681, [Medium](/catalog/medium). Topics: [Hash Table](/catalog/topics/hash-table), [String](/catalog/topics/string), [Backtracking](/catalog/topics/backtracking), [Enumeration](/catalog/topics/enumeration). [View on LeetCode](https://leetcode.com/problems/next-closest-time/description/).

Generate this problem as a practice environment: tested reference solution, 18 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 681   # by problem number
lcpy gen -s next_closest_time   # by problem name
```

## Problem

Given a `time` represented in the format `"HH:MM"`, form the next closest time by reusing the current digits. There is no limit on how many times a digit can be reused.

You may assume the given input string is always valid. For example, `"01:34"`, `"12:09"` are all valid. `"1:34"`, `"12:9"` are all invalid.

### Examples

```
Input: time = "19:34"
Output: "19:39"
Explanation: The next closest time choosing from digits 1, 9, 3, 4, is 19:39, which occurs 5 minutes later. It is not 19:33, because this occurs 23 hours and 59 minutes later.
```

```
Input: time = "23:59"
Output: "22:22"
Explanation: The next closest time choosing from digits 2, 3, 5, 9, is 22:22. It may be assumed that the returned time is next day's time since it is smaller than the input time numerically.
```

### Constraints

* `time.length == 5`
* `time` is a valid time in the form `"HH:MM"`.
* `0 <= HH < 24`
* `0 <= MM < 60`

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/next_closest_time/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/next_closest_time/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(24 * 60 * 4) = O(1)
    # Space: O(1)
    def next_closest_time(self, time: str) -> str:
        allowed = {c for c in time if c != ":"}
        current = int(time[:2]) * 60 + int(time[3:])
        while True:
            current = (current + 1) % (24 * 60)
            candidate = f"{current // 60:02d}:{current % 60:02d}"
            if all(c in allowed for c in candidate if c != ":"):
                return candidate
```

## Complexity

| Time | Space |
| - | - |
| O(24 \* 60 \* 4) = O(1) | O(1) |

## Tags


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